4-hydroxyphenylpyruvate dioxygenase (4-HPPD) is a new action target of herbicides discovered in the 1980s and widely exists in various aerobic organisms. This enzyme is a dioxygenase containing iron divalent and relying on α-ketonic acid. It can catalytically convert p-hydroxyphenylpyruvic acid into homogentisic acid. The action mechanism of 4-HPPD herbicide is a process of inhibiting conversion of p-hydroxyphenylpyruvic acid inside plants into homogentisic acid. The homogentisic acid inside plants can be further biologically catalyzed into plastoquinone and tocopherol, while plastoquinone and tocopherol are substances necessary for transfer of electron chain in plant photosynthesis. If 4-HPPD in plants is inhibited, the synthesis of homogentisic acid will be obstructed, thus affecting the transfer of electron chain of photosynthesis in plants. Consequently, the plants will suffer whitening and die.
Designing and synthesizing 4-HPPD inhibitor with a new structure is one of the hotspot fields for pesticide chemical research in the recent years. By now, 4-HPPD inhibitors with more than five different structures have been discovered and mainly include triketone type, pyrazole type, isoxazole type, diketone nitrile type and benzophenone type. The herbicides developed with 4-HPPD as a target have a string of advantages, such as: high performance, low toxicity, environmental friendliness, and safety to subsequent crops. Therefore, 4-HPPD herbicides have a great research value and development prospect and also attract more and more pesticide companies to the R&D of 4-HPPD herbicides. On the market, there are many kinds of triketone-type 4-HPPD inhibitors. Their molecules all have a benzene ring structure, such as: mesotrione and sulcotrione. Among them, mesotrione has the best herbicidal effect and high safety.
Based on the research on 4-HPPD herbicide system, the present invention designs and synthesizes a new triketone-type 4-HPPD compound containing quinazolinedione structure.